Biallelic MFSD2A variants associated with congenital microcephaly, developmental delay, and recognizable neuroimaging features

Major Facilitator Superfamily Domain containing 2a (MFSD2A) is an essential endothelial lipid transporter at the blood-brain barrier. Biallelic variants affecting function in MFSD2A cause autosomal recessive primary microcephaly 15 (MCPH15, OMIM# 616486). We sought to expand our knowledge of the phenotypic spectrum of MCPH15 and demonstrate the underlying mechanism of inactivation of the MFSD2A transporter. We carried out detailed analysis of the clinical and neuroradiological features of a series of 27 MCPH15 cases, including eight new individuals from seven unrelated families. Genetic investigation was performed through exome sequencing (ES). Structural insights on the human Mfsd2a model and in-vitro biochemical assays were used to investigate the functional impact of the identified variants. All patients had primary microcephaly and severe developmental delay. Brain MRI showed variable degrees of white matter reduction, ventricular enlargement, callosal hypodysgenesis, and pontine and vermian hypoplasia. ES led to the identification of six novel biallelic MFSD2A variants (NG_053084.1, NM_032793.5: c.556+1G>A, c.748G>T; p.(Val250Phe), c.750_753del; p.(Cys251SerfsTer3), c.977G>A; p.(Arg326His), c.1386_1435del; p.(Gln462HisfsTer17), and c.1478C>T; p.(Pro493Leu)) and two recurrent variants (NM_032793.5: c.593C>T; p.(Thr198Met) and c.476C>T; p.(Thr159Met)). All these variants and the previously reported NM_032793.5: c.490C>A; p.(Pro164Thr) resulted in either reduced MFSD2A expression and/or transport activity. Our study further delineates the phenotypic spectrum of MCPH15, refining its clinical and neuroradiological characterization and supporting that MFSD2A deficiency causes early prenatal brain developmental disruption. We also show that poor MFSD2A expression despite normal transporter activity is a relevant pathomechanism in MCPH15

Sequence Diversities of Serine-Aspartate Repeat Genes among Staphylococcus aureus Isolates from Different Hosts Presumably by Horizontal Gene Transfer

BACKGROUND: Horizontal gene transfer (HGT) is recognized as one of the major forces for bacterial genome evolution. Many clinically important bacteria may acquire virulence factors and antibiotic resistance through HGT. The comparative genomic analysis has become an important tool for identifying HGT in emerging pathogens. In this study, the Serine-Aspartate Repeat (Sdr) family has been compared among different sources of Staphylococcus aureus (S. aureus) to discover sequence diversities within their genomes. METHODOLOGY/PRINCIPAL FINDINGS: Four sdr genes were analyzed for 21 different S. aureus strains and 218 mastitis-associated S. aureus isolates from Canada. Comparative genomic analyses revealed that S. aureus strains from bovine mastitis (RF122 and mastitis isolates in this study), ovine mastitis (ED133), pig (ST398), chicken (ED98), and human methicillin-resistant S. aureus (MRSA) (TCH130, MRSA252, Mu3, Mu50, N315, 04-02981, JH1 and JH9) were highly associated with one another, presumably due to HGT. In addition, several types of insertion and deletion were found in sdr genes of many isolates. A new insertion sequence was found in mastitis isolates, which was presumably responsible for the HGT of sdrC gene among different strains. Moreover, the sdr genes could be used to type S. aureus. Regional difference of sdr genes distribution was also indicated among the tested S. aureus isolates. Finally, certain associations were found between sdr genes and subclinical or clinical mastitis isolates. CONCLUSIONS: Certain sdr gene sequences were shared in S. aureus strains and isolates from different species presumably due to HGT. Our results also suggest that the distributional assay of virulence factors should detect the full sequences or full functional regions of these factors. The traditional assay using short conserved regions may not be accurate or credible. These findings have important implications with regard to animal husbandry practices that may inadvertently enhance the contact of human and animal bacterial pathogens

Inhibition of Hypoxia-Inducible Factor-1α (HIF-1α) Protein Synthesis by DNA damage inducing agents

10.1371/journal.pone.0010522PLoS ONE55

HIF-Independent Regulation of Thioredoxin Reductase 1 Contributes to the High Levels of Reactive Oxygen Species Induced by Hypoxia

Cellular adaptation to hypoxic conditions mainly involves transcriptional changes in which hypoxia inducible factors (HIFs) play a critical role. Under hypoxic conditions, HIF protein is stabilized due to inhibition of the activity of prolyl hydroxylases (EGLNs). Because the reaction carried out by these enzymes uses oxygen as a co-substrate it is generally accepted that the hypoxic inhibition of EGLNs is due to the reduction in oxygen levels. However, several studies have reported that hypoxic generation of mitochondrial reactive oxygen species (ROS) is required for HIF stabilization. Here, we show that hypoxia downregulates thioredoxin reductase 1 (TR1) mRNA and protein levels. This hypoxic TR1 regulation is HIF independent, as HIF stabilization by EGLNs inhibitors does not affect TR1 expression and HIF deficiency does not block TR1 hypoxic-regulation, and it has an effect on TR1 function, as hypoxic conditions also reduce TR1 activity. We found that, when cultured under hypoxic conditions, TR1 deficient cells showed a larger accumulation of ROS compared to control cells, whereas TR1 over-expression was able to block the hypoxic generation of ROS. Furthermore, the changes in ROS levels observed in TR1 deficient or TR1 over-expressing cells did not affect HIF stabilization or function. These results indicate that hypoxic TR1 down-regulation is important in maintaining high levels of ROS under hypoxic conditions and that HIF stabilization and activity do not require hypoxic generation of ROS

CCL2-driven inflammation increases mammary gland stromal density and cancer susceptibility in a transgenic mouse model.

Abstract Background Macrophages play diverse roles in mammary gland development and breast cancer. CC-chemokine ligand 2 (CCL2) is an inflammatory cytokine that recruits macrophages to sites of injury. Although CCL2 has been detected in human and mouse mammary epithelium, its role in regulating mammary gland development and cancer risk has not been explored. Methods Transgenic mice were generated wherein CCL2 is driven by the mammary epithelial cell-specific mouse mammary tumour virus 206 (MMTV) promoter. Estrous cycles were tracked in adult transgenic and non-transgenic FVB mice, and mammary glands collected at the four different stages of the cycle. Dissected mammary glands were assessed for cyclical morphological changes, proliferation and apoptosis of epithelium, macrophage abundance and collagen deposition, and mRNA encoding matrix remodelling enzymes. Another cohort of control and transgenic mice received carcinogen 7,12-Dimethylbenz(a)anthracene (DMBA) and tumour development was monitored weekly. CCL2 protein was also quantified in paired samples of human breast tissue with high and low mammographic density. Results Overexpression of CCL2 in the mammary epithelium resulted in an increased number of macrophages, increased density of stroma and collagen and elevated mRNA encoding matrix remodelling enzymes lysyl oxidase (LOX) and tissue inhibitor of matrix metalloproteinases (TIMP)3 compared to non-transgenic controls. Transgenic mice also exhibited increased susceptibility to development of DMBA-induced mammary tumours. In a paired sample cohort of human breast tissue, abundance of epithelial-cell-associated CCL2 was higher in breast tissue of high mammographic density compared to tissue of low mammographic density. Conclusions Constitutive expression of CCL2 by the mouse mammary epithelium induces a state of low level chronic inflammation that increases stromal density and elevates cancer risk. We propose that CCL2-driven inflammation contributes to the increased risk of breast cancer observed in women with high mammographic density

Obesity promotes 7,12-dimethylbenz(a)anthracene-induced mammary tumor development in female zucker rats

INTRODUCTION: High body mass index has been associated with increased risk for various cancers, including breast cancer. Here we describe studies using 7,12-dimethylbenz(a)anthracene (DMBA) to investigate the role of obesity in DMBA-induced mammary tumor susceptibility in the female Zucker rat (fa/fa), which is the most widely used rat model of genetic obesity. METHOD: Fifty-day-old female obese (n = 25) and lean (n = 28) Zucker rats were orally gavaged with 65 mg/kg DMBA. Rats were weighed and palpated twice weekly for detection of mammary tumors. Rats were killed 139 days after DMBA treatment. RESULTS: The first mammary tumor was detected in the obese group at 49 days after DMBA treatment, as compared with 86 days in the lean group (P < 0.001). The median tumor-free time was significantly lower in the obese group (P < 0.001). Using the days after DMBA treatment at which 25% of the rats had developed mammary tumors as the marker of tumor latency, the obese group had a significantly shorter latency period (66 days) than did the lean group (118 days). At the end of the study, obese rats had developed a significantly (P < 0.001) greater mammary tumor incidence (68% versus 32%) compared with the lean group. The tumor histology of the mammary tumors revealed that obesity was associated with a significant (P < 0.05) increase in the number of rats with at least one invasive ductal and lobular carcinoma compared with lean rats. CONCLUSION: Our results indicate that obesity increases the susceptibility of female Zucker rats to DMBA-induced mammary tumors, further supporting the hypothesis that obesity and some of its mediators play a significant role in carcinogenesis

The Nonstructural Proteins of Nipah Virus Play a Key Role in Pathogenicity in Experimentally Infected Animals

Nipah virus (NiV) P gene encodes P protein and three accessory proteins (V, C and W). It has been reported that all four P gene products have IFN antagonist activity when the proteins were transiently expressed. However, the role of those accessory proteins in natural infection with NiV remains unknown. We generated recombinant NiVs lacking V, C or W protein, rNiV(V−), rNiV(C−), and rNiV(W−), respectively, to analyze the functions of these proteins in infected cells and the implications in in vivo pathogenicity. All the recombinants grew well in cell culture, although the maximum titers of rNiV(V−) and rNiV(C−) were lower than the other recombinants. The rNiV(V−), rNiV(C−) and rNiV(W−) suppressed the IFN response as well as the parental rNiV, thereby indicating that the lack of each accessory protein does not significantly affect the inhibition of IFN signaling in infected cells. In experimentally infected golden hamsters, rNiV(V−) and rNiV(C−) but not the rNiV(W−) virus showed a significant reduction in virulence. These results suggest that V and C proteins play key roles in NiV pathogenicity, and the roles are independent of their IFN-antagonist activity. This is the first report that identifies the molecular determinants of NiV in pathogenicity in vivo

Restoring the orangutan in a Whole- or Half-Earth context

Various global-scale proposals exist to reduce the loss of biological diversity. These include the Half-Earth and Whole-Earth visions that respectively seek to set aside half the planet for wildlife conservation or to diversify conservation practices fundamentally and change the economic systems that determine environmental harm. Here we assess these visions in the specific context of Bornean orangutans Pongo pygmaeus and their conservation. Using an expert-led process we explored three scenarios over a 10-year time frame: continuation of Current Conditions, a Half-Earth approach and a Whole-Earth approach. In addition, we examined a 100-year population recovery scenario assuming 0% offtake of Bornean orangutans. Current Conditions were predicted to result in a population c. 73% of its current size by 2032. Half-Earth was judged comparatively easy to achieve and predicted to result in an orangutan population of c. 87% of its current size by 2032. Whole-Earth was anticipated to lead to greater forest loss and ape killing, resulting in a prediction of c. 44% of the current orangutan population for 2032. Finally, under the recovery scenario, populations could be c. 148% of their current size by 2122. Although we acknowledge uncertainties in all of these predictions, we conclude that the Half-Earth and Whole-Earth visions operate along different timelines, with the implementation of Whole-Earth requiring too much time to benefit orangutans. None of the theorized proposals provided a complete solution, so drawing elements from each will be required. We provide recommendations for equitable outcomes

A Single Nucleotide in Stem Loop II of 5′-Untranslated Region Contributes to Virulence of Enterovirus 71 in Mice

BACKGROUND: Enterovirus 71 (EV71) has emerged as a neuroinvasive virus responsible for several large outbreaks in the Asia-Pacific region while virulence determinant remains unexplored. PRINCIPAL FINDINGS: In this report, we investigated increased virulence of unadapted EV71 clinical isolate 237 as compared with isolate 4643 in mice. A fragment 12 nucleotides in length in stem loop (SL) II of 237 5'-untranslated region (UTR) visibly reduced survival time and rate in mice was identified by constructing a series of infectious clones harboring chimeric 5'-UTR. In cells transfected with bicistronic plasmids, and replicon RNAs, the 12-nt fragment of isolate 237 enhanced translational activities and accelerated replication of subgenomic EV71. Finally, single nucleotide change from cytosine to uridine at base 158 in this short fragment of 5'-UTR was proven to reduce viral translation and EV71 virulence in mice. Results collectively indicated a pivotal role of novel virulence determinant C158 on virus translation in vitro and EV71 virulence in vivo. CONCLUSIONS: These results presented the first reported virulence determinant in EV71 5'-UTR and first position discovered from unadapted isolates